1. Field of the Invention
The present invention relates to a discharge valve device having a structure in which a discharge valve part is formed at one end of a bag part made of a film for discharging a gas with which the bag part is filled, the discharge valve part is bent to block a flow of the gas and the discharge valve part is opened to discharge the gas, and relates to a gas cushioning material which is used as a gas cell type cushioning material utilizing the above discharge valve part for an air mat, an air sitting mat, an air pillow and a bale-package material and which can be used as a sleeping bag, an article against the cold, a simplified tent, a simplified awning, and which can be preserved by easily discharging the gas from a gas cell after used and can be conveniently used by filling the gas cell with the gas when used again.
2. Discussion of Related Art
Hitherto, an air injection type air cell cushioning material has been known as a packing material having a cushioning function caused by air. This air injection type air cell cushioning material has the structure in which two films are heat-sealed, a plurality of air cells are in communication with each other and a simple air inlet is formed at an end portion. Usually, after air is injected through the inlet of this end portion, the inlet is heat-sealed.
In the step in which the user uses the air cell cushioning material, due to the above, if the user injects air into the air cell cushioning material by himself or herself, since there is a need to purchase an air injector on which heat seal equipment is formed and the air injector provided with the heat seal equipment has a relatively large size, it is difficult for an ordinary user to conveniently use an air cell cushioning material.
Here, a check valve (for example, see Japanese patent application laid-open publication No. 2005-509568) having a simple structure is mounted to an air injection type air cell cushioning material, and the air cell is filled with air by a simple air pump to utilize the air cell cushioning material. In this air injection type air cell cushioning material, an intermediate film is inserted into an end portion of a cushioning main body formed by overlapping two films, an inclined passage and a check valve part are formed in the cushioning main body, and a gas is injected into each air cell through this check valve part. Consequently, this air injection type air cell cushioning material is used as a cushioning material.
Basically, in this air injection type air cell cushioning material, after the check valve part is mounted to some of the air cells which have a closed periphery, and air is injected into the air cell through the check valve part to fill the air cell with air, air cannot be discharged from the air cell.
Due to the above, after the air cell cushioning material is utilized for bale-packaging the goods, in a case in which the user discharges air from the air cell to preserve the cushioning material while a volume is reduced, the air cell should be broken in order to discharge air from the air cell. Consequently, the air cell cushioning material cannot be filled with air and used again.
In addition, if the air cell cushioning material is used again after used once, the air cell cushioning material is preserved in a state in which the air cell is filled with air and is then used again. Therefore, the air cell cushioning material which is fully filled with air will inevitably have a large volume, and as a result, a large space should be required for preserving the air cell cushioning material.
Because of the above, after the air cell cushioning material is used for bale-packaging the goods, the film constituting the air cell is generally broken and then discarded, and after using the air cell cushioning material for bale-packaging the goods, the user discharges air from the air cell to reduce a volume of the air cell cushioning material and then to preserve it. In the case in which the user uses air cell cushioning material again, it is impossible to perform the above procedure.
Here, the present applicant has proposed the air cushioning material formed of a film and disclosed in PCT International Publication No. WO2014/069209, in which air can be easily discharged from a bag part to preserve the air cushioning material and the bag part can be filled with air to allow the air cushioning material to be conveniently used again. In this air cushioning material, a discharge valve part having a narrowed discharge passage is formed at a portion of a bag part to discharge air from the bag part formed of a film, the discharge valve part is bent and the discharge part is adhered by an adhesive layer formed on a surface of the bag part to close the discharge passage when the bag part is filled with air, and the adhesive layer is detached to open the discharge passage when air is discharged from the bag part.
By detaching the adhesive layer to open the discharge valve part, the air is discharged from the bag part and such an air cushioning material may be preserved and used again. However, if oil, moisture or a foreign substance is contained in the adhesive layer, coupling of the discharge valve part is insufficient so that it is difficult to use the air cushioning material again.